Definition - What does Refractive Index mean?
Refractive Index is the ratio of the velocity of light traveling in a vacuum with respect to the velocity of light inside any medium or any material. Refractive index is also explained by Snell’s Law as the ratio of sine of the angle of incidence to the sine of the angle of refraction. This term is mostly used in Geophysics.
Petropedia explains Refractive Index
Refractive index is denoted as “n” and is a dimensionless quantity. It is a measure of ray of light which bends when it passes from one medium to other medium. Refractive Index is also known as Index of Refraction.
In the diagram below, “I” is called the angle of incidence when light travels in vacuum and when same light passes through any medium, this angle of incidence is converted to angle of refraction “r”.
Now the refractive index “n” is expressed as ratio of sine of angle of incidence to sine of angle of refraction.
n = sin i / sin r.